The immediate objective of this project is to show that the old and patients with auto-immune diseases have lymphocytes which are reactive with self HLA antigens and which play a pathogenic role. The long term objective is to show that potentially HLA auto-reactive cells are also in normal individuals and play a physiological role. Another immediate objective is to show that in some neoplasias of the lymphoid system, the neoplastic lymphocyte is reactive with self HLA Ag or, more likely, with an allo-HLA Ag.